/* --- Header / Nav --- */
    .header {
      position: sticky;
      top: 0;
      z-index: 100;
      background: oklch(from var(--color-bg) l c h / 0.92);
      backdrop-filter: blur(16px);
      -webkit-backdrop-filter: blur(16px);
      border-bottom: 1px solid oklch(from var(--color-text) l c h / 0.08);
      transition: box-shadow var(--transition);
    }
    .header--scrolled { box-shadow: var(--shadow-sm); }
    .header-inner {
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding-block: var(--space-4);
      gap: var(--space-6);
    }
    .logo {
      display: flex;
      align-items: center;
      gap: var(--space-3);
      flex-shrink: 0;
    }
    .logo-mark {
      width: 42px;
      height: 42px;
      flex-shrink: 0;
    }
    .logo-text {
      display: flex;
      flex-direction: column;
      line-height: 1.2;
    }
    .logo-name {
      font-family: var(--font-display);
      font-size: var(--text-lg);
      font-weight: 700;
      color: var(--color-primary);
    }
    .logo-tagline {
      font-size: var(--text-xs);
      color: var(--color-text-muted);
      letter-spacing: 0.08em;
      text-transform: uppercase;
    }
    
    nav { display: flex; align-items: center; gap: var(--space-8); }
    nav a {
      font-size: var(--text-sm);
      color: var(--color-text-muted);
      font-weight: 500;
      transition: color var(--transition);
      white-space: nowrap;
    }
    nav a:hover { color: var(--color-primary); }
    
    .header-cta {
      display: flex;
      align-items: center;
      gap: var(--space-3);
    }
    .btn {
      display: inline-flex;
      align-items: center;
      gap: var(--space-2);
      padding: var(--space-2) var(--space-5);
      border-radius: var(--radius-md);
      font-size: var(--text-sm);
      font-weight: 600;
      transition: all var(--transition);
      white-space: nowrap;
      min-height: 44px;
    }
    .btn-primary {
      background: #1a1512;
      color: #fff;
    }
    .btn-primary:hover { background: var(--color-primary-hover); transform: translateY(-1px); box-shadow: var(--shadow-md); }
    .btn-primary:active { transform: translateY(0); }
    .btn-accent {
      background: var(--color-accent);
      color: #fff;
    }
    .btn-accent:hover { background: var(--color-accent-hover); transform: translateY(-1px); box-shadow: var(--shadow-md); }
    .btn-outline {
      border: 1.5px solid oklch(from var(--color-primary) l c h / 0.3);
      color: var(--color-primary);
    }
    .btn-outline:hover { border-color: var(--color-primary); background: var(--color-primary-light); }
    
    .theme-toggle {
      width: 40px;
      height: 40px;
      display: flex;
      align-items: center;
      justify-content: center;
      border-radius: var(--radius-full);
      color: var(--color-text-muted);
      transition: all var(--transition);
    }
    .theme-toggle:hover { background: var(--color-surface-offset); color: var(--color-text); }
    
    /* Mobile menu toggle */
    .menu-toggle {
      display: none;
      width: 40px; height: 40px;
      align-items: center; justify-content: center;
      border-radius: var(--radius-md);
      color: var(--color-text);
    }